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Magnesium alloys are prone to high-temperature corrosion and lose their mechanical properites in high-temperature environments.Hence，painting high temperature anti-corrosion coatings on magnesium alloy surface to prevent high temperature corrosion is of great significance for improving the durability of parts.In this paper，the concept and classification of high temperature resistant anti-corrosion coatings were expounded，and the research progresses of organic high temperature resistant coatings，inorganic high temperature resistant coatings and organic-inorganic composite high temperature resistant coatings were reviewed.In addition，the application statuses of high-temperature anticorrosion coatings on magnesium alloys were introduced，and their development trend in the future was prospected.

1.5 μm emission and green upconversion emission properties in In/Er-codoped LiNbO3 crystals were investigated by using both steady-state and time-resolved emission spectra. The 1.5 mol % In2O3 codoping results in the lengthening of 1.5 μm emission lifetime by 13.9% and simultaneously the shortening of 550 nm green upconversion emission lifetime by 52.5%. The decay behavior of the green upconversion emission of the In/Er-codoped crystal shows obviously nonexponential. These spectroscopic characteristics are related with the lower concentration of the cluster sites of Er3+ ion and possible cross-relaxation energy transfer processes. The above emission results are further supported by the theoretical emission results based on Judd–Ofelt theory. [ABSTRACT FROM AUTHOR]

Observed is 15 times enhancement of Ho3+ green upconversion (UC) emission in Ho3+(0.75 mol %)/Nd3+(0.75 mol %) doped lithium niobate crystal after incorporating with 4 mol % of Yb3+ under 800 nm femtosecond laser excitation. Yb3+ acting as bridging ion increases the energy transfer efficiency from Nd3+ 4F3/2 level to Ho3+ in these triply doped systems. The nonradiative energy transfer efficiency from Nd3+ 4F3/2 to Yd3+ 2F5/2 level can reach to 56%. The UC emission mechanisms are proposed based on spectral, kinetic, and pump power dependence analyses. The green UC emission is accomplished through a multi-ion interaction involving ground state absorption by the Nd3+ (4I9/2→2H9/2,4F5/2) followed by three successive energy transfer processes involving one Nd3+-Yb3+ (4F3/2+2F7/2→4I9/2+2F5/2) and two Yb3+-Ho3+ pairs (2F5/2+5I8→2F7/2+5I6 and 2F5/2+5I6→2F7/2+5S2,5F4); whereas the red is dominated by excited state absorption of the Ho3+ (5I7→5F5) following two successive energy transfer processes involving the Nd3+-Yb3+ (4F3/2+2F7/2→4I9/2+2F5/2) and Yb3+-Ho3+ pairs (2F5/2+5I8→2F7/2+5I6) followed by the Ho3+ nonradiative relaxation to 5I7. [ABSTRACT FROM AUTHOR]

Congruent LiNbO3 crystals doped with 5.5/1, 6/0.15, and 7/0.8 mol %/mol % of Zn/Er were thermally treated at 1120 °C over 101 h using vapor transport equilibration (VTE) technique. Unpolarized visible and infrared absorption spectra of the VTE-treated and corresponding as-grown crystals were recorded at room temperature. It is shown that VTE treatment has brought these crystals closer to stoichiometric composition. X-ray powder diffraction and optical absorption results show that the VTE treatment induces the crystalline phase transformation with respect to Er3+ from the original Er3+:LiNbO3 to the ErNbO4 in all crystals studied. The formation of the ErNbO4 phase results in substantial absorption changes that include the drop of the transparency in the visible region, the reduction of Er3+ absorption, and the Zn-doping-level-dependent changes in spectral shape and peaking position at 0.98 and 1.5 μm regions. Based upon the measured absorption spectra, the influences of Zn-doping level and VTE treatment on the Er3+ spectroscopic properties were studied by using the Judd-Ofelt (JO) theory. The results show that the VTE treatment has a little effect on the fluorescence branch ratio, while a large effect on the JO parameters, oscillator strength, and electron transition probability. The Zn doping level affects the JO parameters, oscillator strength, and transition probabilities of some individual manifolds. In addition, the VTE treatment leads to the increases of the theoretical radiative lifetimes of almost all manifolds considered. For the emission at 1.5 μm, the lifetime increase is as much as 30% and the theoretical results are in well agreement with the experimental data. The VTE-induced lifetime increase is qualitatively explained. [ABSTRACT FROM AUTHOR]

Mg:Ru:Fe:LiNbO3 crystals with various concentrations of MgO (in mole) and fixed content of RuO2 and Fe2O3 (in mass) are grown with the Czochralski method from the congruent melt. Their infrared transmission spectra are measured and discussed to investigate the defect structure. With the increase of Mg2+ concentration the blue nonvolatile holographic storage capability is enhanced. The nonvolatile holographic storage properties of dual-wavelength recording of Mg(7 mol%):Ru:Fe:LiNbO3 nonvolatile diffraction efficiency, response time, and nonvolatile sensitivity reach 59.8%, 70 s, and 1.04 cm/J, respectively. Comparing Mg(7 mol%):Ru:Fe:LiNbO3 with Ru:Fe:LiNbO3 crystal, the response time is shortened apparently. The nonvolatile diffraction efficiency and sensitivity are raised largely. The mechanism in blue photorefractive nonvolatile holographic storage is discussed. [ABSTRACT FROM AUTHOR]

Congruent Er:Mg:LiNbO3 crystals were grown by the Czochralski method from the melts containing fixed 0.5 mol% Er2O3 while varied MgO content ranged from 0.0 to 8.0 mol%. The Mg and Er contents in the crystals were determined by neutron activation analysis. In the presence of Er codopant, the Mg threshold concentration with respect to optical damage is determined from the measured OH absorption spectra. The results show that the Er codopant has less effect on both the Mg threshold concentration and Mg segregation coefficient, which is within 1.13–1.23 as the Mg concentration is below the threshold while within 0.88–0.98 when above the threshold, consistent with the only MgO doping case. On the other hand, the practical Er concentration in the crystal is closely related to the Mg content and shows definite Mg threshold effect. Below the threshold, the Er concentration decreases linearly with the increased Mg concentration in the crystal; above the threshold, the decrease is more remarkable and follows another linear function. The Mg concentration effect on the Er segregation coefficient is discussed from the viewpoint of the Mg doping effect on the solubility of Er ions in the crystal. [ABSTRACT FROM AUTHOR]

A series of Ho:LiNbO3 crystals with various concentration of Ho2O3 were grown by Czochralski technique. Transmittance spectrum, absorption spectrum and modified Judd–Ofelt approach have been used to investigate its spectroscopic properties. Ho concentrations in crystals were analyzed by an inductively-coupled plasma optical emission spectrometry (ICP-OE/MS). The results of the spectroscopic analysis of transition strengths for Ho ion in a series of Ho:LiNbO3 crystals with various Ho content are reported. It is concluded that all the Ωλ values of the Ho ion decrease with increasing Ho content. For Ho (4 mol%): LiNbO3, the obtained intensity parameters and radiative lifetime of the 5I5 level are: Ω2=5.75×10-20 cm2, Ω4=22.69×10-20 cm2, Ω6=14.10×10-20 cm2, and τ=4.08 ms respectively. The results showed that the Ho2O3-codoped LiNbO3 crystal increases the Ho ion radiative lifetimes, but has less influence on the fluorescence branching ratio. [ABSTRACT FROM AUTHOR]

At 1100 °C, the diffusion properties of Ti4+ into congruent LiNbO3 crystals codoped with 0.5 mol% Er2O3 and different MgO concentrations of 0.5, 1.0, and 1.5 mol% have been studied by secondary ion mass spectrometry (SIMS). Three Y-cut and three Z-cut plates with different Mg doping levels were coated with a 60-nm-thick Ti film at first and then annealed at 1100 °C for 28 h in a wet O2 atmosphere. SIMS was used to analyze depth profile characteristics of diffused Ti ions and the constituent elements of the substrate as well. The results show that the diffusion reservoir was exhausted and the Ti metal film was completely diffused. All measured Ti profiles follow a Gaussian function. No Mg out-diffusion accompanied the Ti in-diffusion procedure for all crystals studied. The 1/e diffusion depth is similar to 8.3/10.2, 7.4/8.7, and 6.6/8.2 ± 0.2/0.2 μm/μm for the Y/Z-cut crystal with the Mg doping level of 0.5, 1.0, and 1.5 mol%, respectively, yielding a Ti4+ diffusivity of 0.62/0.93, 0.49/0.67, and 0.39/0.60 ± 0.03/0.03 (μm2/h)/(μm2/h), respectively. The diffusion shows definite anisotropy and a considerable MgO doping level effect. Under the same Mg doping level, the diffusion in a Z-cut crystal is faster. The diffusivity decreases with the increase of the Mg doping level. This effect is qualitatively explained from the viewpoint of the Mg doping effect on concentration of the intrinsic defects in LiNbO3 crystal. [ABSTRACT FROM AUTHOR]

Hf:Fe:LiNbO3 crystals were grown by the Czochralski technique with various ratios of Li/Nb = 0.946, 1.05, 1.20 and 1.38 in the melt. The crystal composition and defect structure were analyzed by XRD, UV-Vis and IR spectroscopy. The results show that the threshold concentration of Hf in LiNbO3 crystals decrease with the increasing of the Li/Nb ratio; when the Li/Nb ratio is 1.05, the threshold concentration of Hf is less than 2 mol%, largely under the threshold concentration of Hf ions in congruent Hf:Fe:LiNbO3 crystal (4 mol).1–3 With the increase of Li/Nb, Hf ions first replace the ${\rm Nb}^{4+}_{\rm Li}$; when the concentration of Hf ions is higher than the threshold value, Hf ions occurs on normal Nb and Li sites. [ABSTRACT FROM AUTHOR]